Thermo King SLXi Spectrum, Maintenance Manual

Page: 236 / 342

REFRIGERATION SYSTEM COMPONENTS
NOTE: It is generally good practice to replace the filter drier whenever the high side is opened or when the low side is opened
for more than 30 minutes. Replace the external mounted compressor oil filter whenever the filter drier is replaced. This is not
required for units with P compressor with internal oil filter.
TG-VI, µP-IV, µP-V, µP-VI, SR-2 and SR-3 NOTE: A Service Test mode on these controllers allows technicians to operate
the unit under known conditions while performing diagnosis and service procedures. See the appropriate Controller
Operation and Diagnosis manual for instructions on how to use the Service Test mode.
Low Side Pump Down
NOTE: Operate all the evaporators in Cool for 10 minutes or more with the service valves in their normal operating positions
before performing the low side pump down. Install a gauge manifold at the compressor.
1. Run all the evaporators in cool, front seat the receiver tank outlet valve and the bypass hand valve, and pump down the low
side to 20 to 25 in. Hg vacuum (-68 to -85 kPa). Turn the unit Off. If the unit pumps down acceptably and then holds at least
15 in. Hg vacuum (-51 kPa) for 2 minutes or more, it can be assumed that the receiver tank outlet valve, the compressor
discharge valve plates, the HGS solenoid, the HGS2 solenoid, the HGS3 solenoid, the Hot Gas ByPass Valve solenoid (when
applicable) and the purge valve solenoid are sealing acceptably.
2. Prepare to perform service on the unit’s low side by equalizing the high side and low side pressures.
a. Disconnect the purge valve solenoid wires from the main wire harness.
b..Disconnect the hot gas bypass valve solenoid wires from the main wire harness (if applicable).
NOTE: If the purge valve solenoid wires and hot gas bypass valve solenoid wires are not disconnected from the main wire
harness, the purge valve and hot gas bypass valve can become energised when the unit is placed in the Evacuation Test. This
allows the refrigerant in the condenser to flow into the accumulator, undoing the low side pump down.
c. Place the unit in the Evacuation Test. Refer to the appropriate Microprocessor Diagnostic Manual. The high and low side
pressures should equalize in the Evacuation Test.
NOTE: Repeat the pump down procedure if the pressures equalize above 20 psi (138 kPa). If suitably low pressures cannot
be achieved after the third pump down, the refrigerant must be recovered to perform service on the low side.
d.If the reading on the gauge manifold’s high pressure gauge increases after the high and low side pressures have been
equalized, the condenser inlet check valve is leaking.
NOTE: Remember to reconnect the purge valve solenoid wires to the main wire harness when the service procedures have
been completed.
Compressor
Removal
1. Pump down the compressor and equalize the pressure to 0 psig (0 bar). Ensure that pressure holds 0 psig and front seat the
discharge and suction service valves to isolate the compressor from the circuit. Recover remaining refrigerant from the
compressor before moving to next steps.
2. Loosen and remove the compressor/electric motor belt from the Electric Motor pulley (SLe Model 50 and all SLX, SLXe and
SLXi units).
3. Unbolt and remove compressor oil filter bracket from flywheel housing (optional).
4. Unbolt the discharge valve and the suction valves from the compressor.
5. Keep the compressor ports covered to prevent dust, dirt, etc., from falling into the compressor.
6. Disconnect all high pressure cutout switch wires. Disconnect the pilot solenoid valve line. (SLX, SLXe and SLXi - remove
compressor belt guard)
7. Support compressor and remove the compressor mounting bolts from flywheel housing.
8. Lift the service valves out of the way.
9. Slide the compressor to the left until coupling pins are clear.
10. Remove the compressor from the front of the unit.
NOTE: When the compressor is removed from the unit, note the oil level or measure the oil removed from the compressor.
Add the same amount of oil to the replacement compressor.
11. Remove clutch from compressor crankshaft on Model 50 units, from drive coupling on model 30 units.